Were there two versions of the DeLorean BEFORE it
went into production? I think so, as follows are pictures and
supporting information to back my claim. I have put colored arrows
on the images to highlight similarities and differences between the
three versions. Please be patient. Images will take a while
to load.

Prototype

The original prototype was very
visually similar to the final DeLorean. Here are some of
the differences. Follow the arrows. Originally there was no louver
(purple arrow) The car also had sliding windows (blue) with a
"notch" in the back corner and were not lined up
evenly with the rear quarter windows. The side mirrors were shaped
differently and placed farther back (orange). The trim on the
underside on the car was painted to match the Stainless Steel
(red). The rear air vents were two piece (cyan). The front grill
was a smooth piece of black plastic (yellow). Also note
the wheel style that was on the original DMC (green).

Other changes: The side marker lights are just under the
black side strip, and the interior was completely different, not
just in styling but also in color (the interior was a nice 70's
brownish/orange color...nice).

The side marker lights were moved up slightly and
incorporated into the black side trim. The interior of this car
was more in line with the production car. The only major
difference that I have seen between this car and the production
are shown below and are the size and placement of the ashtray,
the lack of a storage "hole" in the center console,
and the shape of the steering wheel (2 spoke as opposed to 3
spoke on the production).

Pre-Production

The Pre-production car is an
interesting mix between the Prototype and the Production
car. To the car were added the louvers (purple). The side
mirrors were moved forward and given a more streamlined look (orange).
The windows kept the with the sliding feature, but were also
made more streamlined. Note how the front and rear windows now
line up on the bottom (blue). Due to stainless changing colors
slightly after it is brushed, the matching fascia and back were
changed, and the under car trim was changed to flat black (red).
The air vents in the sides of the car were changed to a single
piece (cyan). and the front grill was given grooves to make it
look more like a, well, a grill (yellow). The wheels were
changed to a different style (green). The back quarter windows
still were lacking the air scoops that ended up on the
production car (white).

Production

And finally the production car!
The manual sliding windows were removed in favor of the
"tool booth" power windows (blue). The air scoop was
added to the rear quarter window (to help draw air into the
engine?) (cyan). Basically everything else on the outside of the
car stayed intact from the pre-production car to the production
version. again note that the lower trim is flat black
(red).

This is the interior of a early model production De Lorean
(you can kind of make out the built in clock just in front of
the automatic gear shift selector. The steering wheel was
changed to that shown to the left (white) as well as the ashtray
being "rotated" and moved to the right (white). The
louvers were kept on the car (although originally intended to be
a GT option) as they helped to cool the engine (purple).